Tube-corrugating apparatus.



L. H. BRINKMAN.

TUBE CGRRUGATING APPARATUS.

APPLICATION FILED JAN. 11,1913.

' Patented DEC. 8, 1914.

2 SHEETS-SHEET 1.

L. H. BRINKMAN. TUBE GORRUGATNG APPARATUS.

APPLIOATION FILED JAN. 11,1913.

Patented Deo. 8, 1914.

2 SHEETS-SHEET 2.

WITNESSES.- nvr/15N TOR,

- y an erarns rairnur oberen LOUIS H. BRINKMAN, OF GLEN RIDGE, NEWJERSEY, ASSIGNOB- TO BALTIMORE TUBE COMPANY, OF BALTIMORE, MARYLAND, ACORPORATION OF MARYLAND.

TUBE-CORRUGATING APPARATUS.

Application filed January 11, 1913.

To all whom it may concern Be it known that I, LOUIS H. BRINKMAN, acitizen of the United States, and a resident of Glen Ridge7 county ofEssex, State of New Jerseyfhave invented certain new and usefulImprovements in Tube-Corrugating Apparatus, of which the following is aspecification.

My invention relates to tube-corrugating apparatus, and moreparticularly to' apparatus for corrugatin tubes helically, and one ofthe objects o' 'the invention is the provision of tube corrugatingapparatus which will twist the tube in corrugating or folding it so asto displace the metal in such manner as to ermit tubes to be corrugatedwith deep fol s to render the tubes exceed ingly flexible or provide arelatively great radiating surface.

Another object of the invention is the pro-y vision of tube-corrugatingapparatus by means of which corrugated tubes of considerable length maybe made, the lengths of the corrugated tubes being limited only by thelengths of tubes obtainable to be corrugated.

Another object of the invention is the provision of tube-corrugatingapparatus by the means of which tubes may be corrugated with uniformfolds.

Another object of the invention is the provision of tube-corrugatingapparatus by means of which the tubes may be corrugated with folds ofconsiderable depth without appreciably thickening, stretching orspinning out the metal during the folding process, so that thelthickness of the walls of the tube will be substantially unchangedduring the folding process., l

Other features of the invention are the arrangement and construction ofthe apparatas whereby the corrugated tube may be twisted to'any desireddegree, and whereby the diameter of the corrugated tube will be equal tothe diameter of the tube being corrugated, and whereby the axialsectional configuration of the folds may be varied as desired.

Various apparatus have been proposed for corrugating tubes helically inan attempt to form helicallycorrugated tubes with deep folds to providethe 'flexibility and relatively great radiating surface necessary to'the adaptation of such tubes to the extensive Specification of LettersPatent.

Patenten Dee. e, 1914.

Serial N0. 'lldllr field of uses such, for example, as for flexibleconnections, couplings, radiators, etc., but the methods and apparatusproposed for making such tubes either stretch or crush and stretch themetal into folds without twisting the metal, and this twisting I havefound to be essential in deeply corrugating tubes. The apparatus whichhas been proposed and the methods of operation of the same are such thatthe deeply corrugated tubes desired can not be commerciallymanufactured, and so far as I am aware, heretofore it has beenimpossible to commercially manufacture corrugated tubes with folds orcorrugations of such depth as to render the tubes really flexible, orprovide a relatively great radiating surface.A

By the use of apparatus embodyin my invention helically corrugated tubeso con` siderable length may be readily made, the length of thecorrugated tube being limited only by the length of the tube to becorrugated, and the corrugations or folds may be of extreme depth so asto provide a pipe of great flexibility and relatively large radiatingsurface. By means of apparatus made in accordance with my invention, themetal of the tube is folded in such a manner that it is not wrinkled ormaterially thickened or spun out during the folding process, and by theuse of the preferred form of the invention, the wall thickness of thetube remains substantially unchanged during the folding process. Theseresults are made possible by the provision of means for twisting themetal of the tube, and while twisting it pressing upon it along ahelical line along which the metal will fold, the pressure being exertedupon the wall of the tube at a progressively shifting -short portionthereof and the actual twisting ofthe metal being localized tosubstantially the short portion of the tube being pressed upon or theshort portion being folded, so that the portion of the tube which hasbeen folded to the desired final form is protected from distortion bythe twisting force. The twisting of itself tends to fold the tube bydistorting it helically and contracting it longitudinally, and thusgreatly reduces the pressure required on the metal to deepen the folds,and if continued after the folds are thus formed, it reduces the pitchof the folds and increases their'depth by continuously forcing Ell thefolds around lielically analogous to the manner in which a helicalspring of a certain pitch and diameter may be reduced in. diameter andpitch by slipping it over a rod to prevent buckling, and holding .oneend down on the rod .while twisting the rod and. holding the oppositeend of the spring from rotation, while permitting it to rnove along therod.

ln deeply corrugating tubes, l have found that it is of greatimportance, if not essen' tial, to apply the pressure along the helicalline inwardly against the wall of the tube.

When. the pressure is exerted from the outside inwardly on the tube toform the folds by displacing the ine-tal inwardly, the diameter of thepressed-in metal is less than that the original tube;4 hence there ismore than sufficient metal for the circumferential. measurement of thefolds and the metal does not have to be stretched or-spun out in formingt ie folds as would be the case if. the pressure were exerted from theinside outwardly. The inetal is pressed inwardly and as a result of thisYinward pres-- sure, were it not for twisting of the metal, there wouldbe produced an excess of metal along .the helical line of pressure, suchas taires place when it is attempted. to force the metal of a hollowcylinder or tube in vwardly any point along its length to re'- duce thediameter that -point; in which event, by being cr wded in alongthe lineof reduced diameter,- the metal would be caused .to wrinkle or nuclrer.r1fhis crowd ing of v'he metal would soon limit the depth of the foldsif it werenot for the 'twisting force above mentioned; but by producinga twisting force in the tube to actually twist l, and while tube isunder such iorce, ressing inwar J on it along a heli cai li the excessnietal 1s displaced heir ced inwardly so as to 1 g process, permitting wof great depth.

che metal of a tube to P n j llressure is so ygreat Vthat sufficient.friction between the corrugating tool and the ni. al is produced totwist the tube, and because or this resistance the instal can be Winn-edand drawn .together along tie length of the tube to form the axial sectional configurati n ofthe folds and otheru wise fornied into te-desired shane Without appreciable' stretching or spirniing of themetal..

.lily invention will be more readily under@ stoor" further objects ofthe invention will incre fully appear from the following descriptiontaken in connection with the ad coil j drav ings, in whichv l; a nteleyation of the pre ferrea ornafof T"naratus embodying invention, tubetia` ly uniform in thiclr v with projections 26,27, 28,

ig 2 is an enlarged view ofv a part ofthe mechanism showing thecorrugating tool or die partly in section and in position to commencecorrugating the tube; Fig. 3 is a View showing the die and a part of thecorrugated tube in section; Fig. l is a crosssectional View of the 'dieshown in. Fig. 2, taken on. line 1li- A and looking in the direction.ofthe arrows B; Fig. 5 is' a fragmentary sectional View showing ainodilied forni of corrugating die in process of operation; Figs. 6, 7,8 and 9 show different forms of tube corrugated by said machine; Fig. l0illustrates the manner in which the metal of the tube is twisted orcarried ga around helically as it is being compressed; and vlEig. ll isa diagrammatic illustration.

Referring to the drawings, Fig. l is a front elevation. of a suitablemachine frame l having a head stock 2 and a .tail stock 3.

.4l is a shaft journaled in the head stock and counter pillow block 5and driven through any suitable means such as pulley ti. rlhe inner endof the shaft is provided with a chuch 'l (Fig. 2) to which is secured gcthe tube 8 to be corrugated or folded, and` also an inner support orinandrel `9 which extends through the tube, the tube and inandrel beingsecured to the chuck by any suitable means such as set bolts l0, lG, sothat they will revolve together with the chuck.

A. carriage ll of suitable construction is slidingly mounted on theframe l and is moved longitudinally along the same by ico means of ascrew spindle l2 journaled in the head and tail stocks and driven fromshaft l through suitable gearing 13, the gearing being arranged like theusual lathe gearing so that the speed lof the screw spindle l2 c5 may bevaried, depending upon the work to be performed. 0n the carriage ll ismounted a suitable chuck lll of the usual construction, but in which forthe usual radially adinstable gripping jaws, are substituted raliodially adjustable die sections l5, i6, l?, 18. 'lhese sections are movedradially by adjust. ing pins each carrying at its inner end the usualbevel gear meshing with the gear teeth 20 cut on one side of-ring 2l onthe iis other side of which are formed the spiral threads which meshwith threads 23 for the purpose of moving the` die sections in and outradially to adjust the diameter of the die. ilfhe inner ends of thesedie secizo tions are tapered as shown at 2li in Fig. Il, to permit thedesired radial adjustment, and the inner ends of the sections are`provided 29 which, when the die sections are assembled, form a threadist or helical projection. increasing in height and decreasing in pitchtoward the finishing end of the die. ln the preferred forni of'hevinrention as shown herein, the prof jeetions of each section of thedie constireo w gaten., 1510i.

tute longitudinal sections of a continuous thread or helical projectionprogressively7 increasing in height and decreasing in pltch, so thatwhen the die is assembled, the projections of the different die sectionsform such a helical projection.

In theform of the invention herein shown, a hollow tail shaft 30 isprovided extending through a sleeve 3l journaled in tail stock 3, thetail shaft being secured at its inner end by a suitable chuck 32 to therear end of the tube 8. The purpose of this tail shaft is to produce apositive predetermined twist in the tube being corrugated, and for thispurpose the tail 'shaft is rotated at a speed less than the speed ofshaft 4, the difference in speeds being such as to produce the desiredtwist in the tube while it is being folded. This tail shaft may berotated by any suitable means to produce this result, and in the presentform of the invention the shaft is provided with a groove 331m whichfits a suitable feather (not shown) projecting inwardly from the sleeve31 to cause the shaft to rotate with the sleeve and permitting it tomove longitudinally through the sleeve. The sleeve is driven in anysuitable ;rnanner such, for example, as from screw spindle 12 throughgearing 3l.

The tail shaft is preferably hollow so that the rear end of the mandrel9 may extend into it; but any suitable arrangement may be used fordriving the rear end of the tube in the same direction as the finishingend, but at less speed; in fact, although less desirable results will beobtained, the additional twisting force which is produced by vtherotation of the tail shaft at less speed than the rotation of thefinishing end of the tube, may be obtained by gripping the rear endofthe tube 8 in any suitable manner to retard its rotation, such, forinstance, as by a friction grip which will permit it to be rotated butat less speed than vit would be rotated if it were held back simply bythe friction of the die.

Referring to Figs. 2 and 3, it will be observed that the helical dieteeth or projections are so constructed that the advance projectionsimply initiates in the tube a helical mark or groove along which thetube is to be folded, and by thus starting a groove in the tube it givesit a line of least resistance along which to fold under the twistingforce. lt will also be noted that the advance convolution of the helicalprojection marks out along the length of the tube sufficient metal toform the axial sectional configuration of the desired fold in theultimate product; that is, the distance between points 36 and 37 isequal to the length of the curved outline between points 38 and 29.

By marking out along the tube sufficient metal to form the sectional.outline of a fold of the desired depth and pitch, it is' possible toform the desired folds according to my invention' without appreciablystretching or spinning out the metal. It will be further observed frominspection of these drawings, that the greatest diameter of the helicalthread of the die is the same throughout the length of the thread and isequal to the diameter of the tube to be corrugated. This insures thediameter of the corrugated tube being the same las the original diameterof the tube, since it positively prevents any outward expansion of thetube during the folding process, and the outer surface of the folds maybe made to assume an outline depending upon the outline of the groovesbetween the projections of the die. When a die of this character is usedand relative rotation is produced between the tube and the die while thetube is gripped by the die, the friction produced is so great that thetube is twisted, and as the metal of the tube under this twisting forceand the relative longitudinal movement between the die and the tube, isdrawn through the helical ath or groove in the die, `the helical line aong which the tube is gripped by the advance convolutions of the die isgathered or drawn together in forming the folds. rlhe friction producedby a corrugating tool or die of this character is so great thatsufficient friction is obtained for corrugating tubes of certainsizeswithout the use of an means for retarding the rear end of the tubeor for positively driving it at less speed than the front end to producea positive twisting torce. Tubes as large as 3 inches in diameter andwith walls a thirty-second of an inch thick, have been successfullycorrugated by such dies without any additional rctarding force appliedat the rear of the tube, but the application of a retarding force at therear cud of the tube makes it possible to utilize a tool having lessfriction, and whether or not this be taken advantage of, it producescorrugations of greater uniformity and enables tubes of greater wallthickness to be more readily corrugated.

`vVhen it is desired to form tubes of a given size but with greaterflexibility and larger radiating surface than is possible with the dieshown in Figs. 2 and 3, means may be provided for pressing on the foldsin a direction longitudinally of the tube while they are being formed soas to bend them lengthwise of the tube as shown in Fi s. 5, 8 and 9.This is done in the form o apparatus herein shown `(Fig. 5) by graduallyturning the edges of the helical projections longitudinally at thefinishing end of the die so as to progressively bend the foldslongitudinally as they are being deepened. I have found it preferable tocommence this longitudinal turning over or bendin of the helicalprojections at about one an a half convolutions from the finishing endof the --yield when the mandrel is In the drawungs` herein shown, theman- Y necessarily,

any.,

die and gradually increasing the bent projection until it is of suchlength as to give the desired shape to the ultimate fold. While haveshown these projections with bent edges as an integral part of the diesections, obviously they need not be made integral with the remainingpart of the sections.

Besides obtaining corrugated tubes of greater flexibility and radiatingsurface by bending the folds longitudinally as shown in Figs. 8 and 9,the bending of the folds in this manner enables the corrugated tube tobe more readily drawn from the mandrel, since `the folds, instead ofbearing down perpendicularly upon the mandrel, are inclined or soconstructed that they will more readily being drawn out.

drel is of such diameter with respect t0 the setting of the die, thatthe last tooth of the die folds the tube down upon the mandrel; but ifdesired, the finishing tooth or convo lution need not come down so closeto the mandrel, and the twisting of the tube after it leaves thefinishing end of the die may be relied upon to finish the folding of thetube down upon the mandrel.

The operation of the apparatus herein shown and described is as follows:rl`he tube 8 to be folded is preferably, though not drawn down to ataper near its forward end so as to fit the taper of the die, and thetube is then slipped over the mandrel and the mandrel and tube aresecuredA in the chuck 7 in any suitable manner so as to rotate togetherwith the chuck. The hollow tail shaft 30 (when one is used) is thenpulled forward through the sleeve 31 and -after the rear end of themandrel has been slipped into it, the rear end ofthe tube 8 is securedin the chuck 32, and the carriage 11 being up at the head of the frameto bring the die in the position shown in Fig. 2, the sections of thedie are gradually moved inwardly by turning one of the pins 19 until thehelical projection-formed by the diHerent projections on the diesections, grips the tube along the tapered portion. If power 'is nowthrown on to rotate shaft 4, the mandrel and front end of the tube willbe roand simultaneously therewith the spindle 12 will be rotated to movethe carriage along the tube and to rotate the tail shaft and rear end ofthe tube at a definite predetermined speed less than that at which theforward end of the tube is being rotated so as to positively twist thetube a predetermined definite amount, depending upon the relativerotation between the forward and rear end of the tube. As the die ismoved along the tube, the advance point 36 of the helical projectionprogressively marks or initiates a helical groove in the tube, and themetal marked out by the rst convolution of the helical projection, as,

tated, threaded .exerted on the tube,

iaadaee for example, the metal between points 36 and 37 is graduallydrawn together as the pitch of the helical projection decreases, andsince the height of the projection progressively increases as the pitchdecreases, the metal along the helical line is gradually andprogressively pressed inwardly as the lines along which the tube isgripped by the tool are drawn together; and as the metal is beinggradually forced in by the lhelical projection, the excess metal, due tothe reductiondn the diameter along this line, is gradually displaced bythe twisting force as indicated, by way of illustration, by thedirection of the arrows inlFig. 10.- 'lhis twisting force, as previouslystated, not only displaces this metal under the inward pressure so as topermit the deepening of the grooves to the desired extent withoutwrinkling or rupturingthe metal, but the twisting of the tube in itselftends to fold the tube helically along the line of least resistanceproduced by the helical groove initiated in the tube. As the diecarriage is moved along the tube, the die progressively marks the tubein this manner and the twisting force is continuously ap-` plied asdescribed. The ei'ect of the twisting force in the gradual drawingtogether of the metal of the tube into helical folds may be illustrated,in a way, by reference to Fig. 11, in which 45 is a rod or mandrel tothe end 46 of which is secured a helical spring or piece of spring wirewhich is wound around the rod with a progressively increasing pitch fromthe end 46. If it is attempted to draw the convolutions of the springtoward end 46 so as to decrease the itch of the longer convolutions asshown at the end 46 of the mandrel without rotating the mandrel or thefree end of the spring, as the convolutions say at points 47 and 48, aregripped and drawn together, the convolutions of the spring between thesepoints will rise from the mandrel as shown in dotted lines; but bygripping the convolutions` at the free end of the spring so as to holdthem from rotation, then rotating` the rod in the direction-shown by thearrow 49, and gradually drawing the convolutions .together toward end46, the spring will be twisting force is actually slightly longer thanthe tube would have been if it could have had similar corrugationsformed in it Without the twisting force.

The amount that the tube may be twisted in forming the folds may bevaried in several ways such as by varying the relative rate of rotationof the advance and rear ends of the tube, or by varying the pitch of thedie relative to that of screw shaft 12, or the speeds of the shafts 4and 12. j

in practice I have found that it is very important to provide a supportfor the tube being corrugated, such, for example, as the mandrel. Suchva support is an important feature in regulating the action of thetwisting force on the folds, and by the regulation of this force, foldsof the desired configuration and size may be formed. For example, whenthe finished folds are brought down firmly upon the support and onlysufficient relative rotation between the shafts 4 and 30 is produced todisplace the metal as it is being pressed upon by the die, or to bringthe folds down upon the support after they leave the die, where thesupport is of less diameter than the die, the friction between the foldsand the support is sufficient to prevent relative rotation between thesupport and the folds which have been forced firmly into engagementtherewith, so that the support will serve to localize the twisting forcein the tube by transmitting the force from the chuck to the portion ofthe tube beingr folded down upon the support. By reason of this thefolds that have been brought firmly into engagement with the support areprotected from., further effects of the twisting force, so that the tubemay be deeply corrugated under the twisting force and the pressure ofthe die, without crowding together the folds after they have been forceddown firmly into engagement with the support. If, however, it is desiredto force the folds more or less together to change thesectionalconfiguration of the same, and to decrease their pitch after they havebeen forced firmly into engagement with the support, this may be done byde creasingthe longitudinal travel of the d1e with respect to the pitchof its helix. I have found that without a suitable support, the tubeunder the twisting force necessary to deeply corrugate it, will twist upand buckle, since only a very short length of tube can transmit thetwisting force necessary to overcome the friction ofthe die withoutbeing distorted; and again the corrugations formed would, under suchforce, likewise be twisted and distorted out of the desired shape andsize.

In Fig. 6 the dotted helical line 52 represents the seam of the originaltube which was corrugated, and illustrates the relative amount of twistin the corrugated tube for a given length. If, in corrugating tubes inthe shape shown in F ig. 6, the shaft 4 should be driven at 38revolutions per minute and the tail shaft 30 at 32 revolutions, therewould be a difference of 6 revolutions representing G complete twists inthe tube per minute, and if the pitch of the screw shaft 1:2 and thecorrugated pipe 8 is l inch, the corrugated tube -will have beencompletely twisted G times for every 9i; inches.

Fig. 7 shows the matter in which the folds or corrugations are forcedtogether when the relative diameters of the die and the mandrel are suchthat there is a clearance between the folds of the tube and the mandrelas the folds leave the die, in which case the twisting force duc to therelative rotation of the mandrel with respect to the die, will furthertwist the corrugated tube until the folds are drawn by the twistingforce firmly together, as shown in Fig. 7, or this crowding of the foldsmay be obtained in another way, as previously stated, by decreasing thespeed of the shaft 12.

Fig. 8 shows one form in which tubes may be corrugated with a die havinga portion of its projection near the finishing end bent longitudinallyin the direction of the aiiis of the tube somewhat in the manner shownin Fig. 5, but the teeth or projections of the die being so formed thatone wall of each finished fold is upright while theother wall of thefold is bent in such manner that each fold overhangs on one side theadjacent groove; whereas, in Fig. 9 the entire fold droops over to oneside.

In referring to the helical contour or thread of the tool or die, I haveused the terms helix, helical projection and helical projectionssomewhat synonymously and interchangeably, because the projections ofthc tool or die sections, when assembled, form a continuous helicalprojection; and in so far as the principle of my invention is concerned,it may be regarded as a unitary solid helical projection, or as composedof' a greater or less number of projections than those herein shown. Forconvenience of description, I have also used the terms folds and eachfold in referring to the corrugated or folded tube, since eachconvolution of the helically folded tube may be considered as a fold.

While l have shown and described in detail apparatus which embodies myinvention in its most efficient form, it will be obvious to thoseskilled :in the art that various changes and modifications may be madenot only in the tool or die, but in the machine as a whole, withoutdeparting from the scope and spirit of the invention, and I do not wishto be understood as limiting myself other than as indicated in theappended claims.

` I make no claim herein to my new method o tions each provided Macnee'of corrugating or folding tubing herein described, vor to the newproduct which may be made according to the method and apparatus hereindescribed, since the .method and product are respectively the subjectmatter of my co-pending applications Serial No. 741,387 and Serialll'o;@1,588 led on even date herewith.

1 claim- 1. A tool for corrugating tubes provided with an opening havingan internal thread of a plurality of convolutions decreasing in pitchand increasing in depth toward the finishing end of the tool, themaximum inner diameter of the tool being substantially the sainethroughout its length to limit the outer diameter of the corrugatedtube.

2. A tool for corrugating tubes having an inner helical projection of aplurality of convolutions decreasing in pitch and increasing in heighttoward the finishing end forming with the Wall ofthe tool a helicalgroove of decreasing Width toward the finishing end, the inner diameterof the tool along the helical groove being substantially uniformthroughout.

3. A tool for corrugating tubes having an inner helical projection of aplurality of convclutions decreasing in pitch and increasing in heighttoward the finishing end forming with the Wall of the tool a helicalgroove of decreasing Width toward the linishing end, the distancebetween adjacent edges of the helical projection measured along thebottom or arch of the groove being substantially uniform throughout thetool.

4. A tool for corrugating tubes comprising a plurality ofV radiallyadjustable sections each provided With projections adapted, whenassembled, to form a thread of decreasing pitch and increasing depthtoward the finishing end thereof for gripping the tube to fold it.

5. A tool for corrugating tubes comprising a plurality of radiallyadjustable sections each provided `with longitudinal sections of ahelical projection, of a plurality of convolutions adapted, whenassembled, to form a helical projection and increasing in height towardthe finishing end thereof.

6. A tool for` corrugating tubes comprising'a plurality of radiallyadjustable secalong its inner surface with 'longitudinal sections of acontinuous inner helical projection of a plurality of convolutionsdecreasing in pitch and increasing in height adapted, when assembled, toform such a projection.

7:' A tool for corrugating tubes having a plurality of radiallyadjustable sections each rovided with longitudinal sections "ot aninternal thread having a plurality of convodecreasing in pitch,

lutions decreasing in pitch and increasing in depth adapted, Whenassembled, to form `combination of .t die comprising a plurality ofradially adjustable longitudinal sections having formed along theirlinner surfaces longitudinal sections of a thread of decreasing pitchand increasing depth adapted,

When assembled, to form a thread of. decreasing pitch and increasingdepth toward the finishing end, vand means operatively connectingsaidsections whereby they may be simultaneously adjusted yradially.

10. A tool for corrugating tubes provided with a helix of decreasingpitch toward the finishing end thereof for gripping the tube j helicallyto fold it into helical folds, the fuiishing end of the helix of thetool being inclined longitudinally of the axis of the tool to press aWall of each fold longitudinally in the same direction.

1l. A tool for corrugating tubes provided of the corru- With projectionsarranged to form a heliX of decreasing pitch and increasing heighttoward the finishing end thereof for gripping the tube to fold ithelically, one or more of the projections at the finishing end of thehelix of the tool being inclined longitudinally of the axis of the toolso as to press the helical folds longitudinally.

l2. A tool for corrugating tubes provided with a helical projection of aplurality ofconvolutions decreasing in vpitch and increasing in heighttoward the finishing end thereof for gripping'the tube to gradually foldit helically, the finishing end of the helical projection beingprogressively bent longitudinally ofrthe axis of the tool tobend thefolds of the tube longitudinally While being formed.

`, 13. A tool forcorrugating tubes provided with an inner helicalprojection of a plurality of convolutions decreasing in pitch 'andincreasing in .height-toward the finishing end thereof for grippingv thetube to gradually fold it helically, the edge of the helical projectionalong a portion of its length being progressively bent overlongitudinally of the anis of the tool as the pro- -llO :naaste jectionincreases in-length so that the inner folds of the tubeI areprogressively laid over longitudinally While being deepened.

14. In a machine for corrugating the combination of a tool having anmternal thread of progressively decreasing itch and increasing depthtoward its finis ing end for gripping the metal, means for causingrelative rotation between said tool and tube t0 twist the tube, andmeans for producing relative longitudinal movement between said tool andsaid tube, whereby the tube is progressively gripped and the grippedmetal drawn together into helical folds.

15. In armachine for corrugating tubes, thecombination of a die havingan internal thread of decreasing pitch toward its finishing end forgripping a tube, means producing relative rotation between the tube anddie to twist the tube to cause it to be gathered into helical folds bsaid die, and means inside said tube or limiting the depth of the foldsformed.

16. ln a machine for corrugating tubes, the combination of a tool havingan opening with corrugated walls for gripping a tube, said corrugationsprogressivel decreasing in pitch and increasing in depth toward thefinishing end of the tool, a mandrel extending within the o ening andupon which the tube is folded own, means for rotating the/mandrel andtube to cause the tube to be twisted by the gripping tool until it isfolded down on the mandrel, and means for moving said toollongitudinally of the tube, whereby the tube is progressively grippedand the gripped metal drawn down into helical folds on the mandrel.

17. In a machine for corrugating tubes, the combination of a smoothmandrel to which a tube is secured at one end to rotate therewith, a diesurrounding the tube and mandrel and having an internal helicalprojection decreasing in pitch and increasing in height toward thefinishing end thereof for gripping the outer surface of the tube, andmeans for rotating the mandrel to twist the tube through the die andfold it helically upon the mandrel.

18. In a machine for corrugating tubes, the combination of a die havingan internal helical projection decreasing in pitch toward the finishingend thereof for gripping the outer'surface of a tube, and means fortwistin the tube through the die, said means including a mandrel of thediameter of the finished tube extending within the die and upon whichthe tube is folded down, whereby, after a portion of the tube has beenfolded down on the mandrel, the twisting force is transmitted throughthe mandrel to the portion of the tube being folded.

19. .In a machine for corrugating tubes, the combination of means forpressing upon tubes,

the tube along a helical line, means for ro tating one end-of the tuberelative to the other so as to actually twist the metal of thc tube, andmeans coperating with said pressing means for localizing the twisting ofthe metal to the progressively' shiftingA shoiiis length of the tubewhere pressure is app e 20. In a machine lfor corrugating tubes, thecombination of means for pressing upon the tube along a helical line,means coperating therewith for producing relative rotation between thetube and said pressing means to produce a twisting force in the tube,and means for localizlng the actual twisting of the metal of the tube toa progressively shifting short length of the tube being folded.

21. In a machine for corrugating tubes,. the combination of means forrotating the advance end of a tube, means forrretarding the rotation ofthe rear end so as to twist the tube, and means for progressivelypressing upon the tube along a helical line while it is being twisted,whereby the tube is gradually gathered into helical folds.

22. In a machine for corrugating tubes, the combination of means forsimultaneou'sly rotating the ends of a tube in the same direction atdifferent speeds to produce a twisting force in the tube, and means forinitiating a helical groove in the tube of decreasing pitch and guidingthe metal uuder the twisting force into helical folds.

23. In a machine for corrugating tubes, the 'combination of means forsimultaneously rotating the ends of a tube in the same direction at aconstant predetermined difference in speeds to produce a twisting forcein the tube, and a die having a helical projection decreasing in pitchand increasin in height toward the finishing end thereof to initiate ahelical groove in the tube and draw together the grooved metal under thetwisting force into helical folds.

24. In a machine for corrugating flexible tubes, the combination of adie'having an internal helical projection decreasing in pitch toward thefinishing end thereof for gripping the outer surface of a tube, amandrel extending within the die for receiving the tube, from which thetube may be drawn longitudinally and to which the advance end of thetube is secured, means for rotating the mandrel, means to which the rearend of the tube is secured from relative rotation with respect thereto,but permitting the tube to be drawn in by the die, means for rotatingsaid securing means at less speed than the mandrel', and means for mov-125 ing the die along the tube, whereby the tube is folded helicallyabout the mandrel.

25. In a machine for corrugatng tubes, the combination of means forrotating a tube and means for gripping the outer surface of the rotatingtube helically and gradually gathering the metal of the tube intohelical. folds and bending said folds longitudinally.` l

26. In a machine for corrugatingtubes, the combination et" a helii; ofdecreasing pitch for gripping a tube, means for producing relativerotation between the tube and the helix to cause the tube to beprogressively corrugated helically, and means at the nishing end of thecorrugating helix for engagingthe folds of the corrugated tube to bendthem longitudinally.

27. ln a machine for corrugating tubes, the combination of a toolmovable relatively to the tube adapted to press upon the tube along ahelical line, and means for twisting the tube While it is being pressedupon by the tool by producing relative rotation bemannen twten the toolandthe advanced end of the tu e.

28. ln a machine for corrugating tubes, the combination of a die havinga'helical projection decreasing in pitch and increasing in height towardits finishing end adapted to press upon the tube, and means forproducing relative rotation and longitudinal movement between the tubeand the die to twist the tube and draw the metal together into helicalfolds.A

ln testimony whereof, l have signed my name to this specication, in thepresence of two subscribing Witnesses.

LOUlS BRINKMAN.

Witnesses:

EDWIN SEGER, SAMUEL M. WARD, Jr.

